HUMORAL IMMUNITY,

of new drugs for livestock. See also GOOD

LABORATORY PRACTICES (GLP), NADA.

Good Laboratory Practices (GLP) A set of rules and regulations issued by the Food and Drug Administration (FDA) that establishes broad methodological guidelines for procedures and record keeping. They are to be followed in laboratories involved in the testing and/or preparation of pharmaceuticals. GLPs also apply to the Environmental Protection Agency (EPA) (e.g., in toxicity testing of new herbicides).

Gset of general methodologies, practices, and procedures mandated by the Food and Drug Administration (FDA) which is to be followed in the testing and manufacture of pharmaceuticals. The purpose of GMPs is essentially to provide for record keeping, and in a wider context to protect the public. GMP guidelines exist instead of specific regulations due to the newness of the technol-

ogy, and may later be superceded (modified) due to further advances in technology andGood Manufacturing Practices (GMP) The

understanding. See also cGMP.

Gossypol A yellow pigment produced in glands and seeds of the cotton plant (Gossypium spp.), and some other plants. When consumed by monogastric animals (e.g., swine, poultry, etc.), gossypol is somewhat toxic to those animals. See also COTTON,

PHYTOTOXIN.

GP120 Protein An adhesion molecule (glycoprotein) on the envelope (surface membrane) of HIV (i.e., AIDS-causing) viruses that directly interacts with the CD4 protein on helper T cells; enabling the HIV viruses to bind to and infect helper T cells. In 1994, a group at America’s Scripps Research Institute led by Dennis Burton and Carlos Barbas III announced that they had generated a recombinant human antibody to the GP120 protein; which neutralized more than 75% of HIV isolates against which it was tested. This advance holds the potential to someday lead to a vaccine against AIDS. See also

MONOCLONAL ANTIBODIES (MAb), HUMAN IMMU-

NODEFICIENCY VIRUS TYPE 1 (HIV- 1), HUMAN

IMMUNODEFICIENCY VIRUS TYPE 2 (HIV- 2),

ACQUIRED IMMUNE DEFICIENCY SYNDROME (AIDS),

SOLUBLE CD4, CD4 PROTEIN, HELPER T CELLS

© 2002 by CRC Press LLC

(T4 CELLS), CD44 PROTEIN, ADHESION MOLECULE,

CONSERVED, GLYCOPROTEIN, SELECTINS, LECTINS,

PROTEIN.

GPA1 A gene, found in most plants, responsible for controlling water retention and cell division in those plants. The GPA1 gene codes for a G-protein, which transmits/regulates signals (light, temperature, phytohormones, nutrients, etc.) controlling the plant’s development.

During 2001, Alan Jones and colleagues discovered that “knocking out” (silencing) the GPA1 gene caused the (then-resultant) G-protein to be insensitive to abscisic acid. Because abscisic acid is a phytohormone (plant hormone) utilized by plants to control the size of stomatal pores [i.e., the openings in leaves through which plants exchange oxygen and carbon dioxide (and also water inadvertently) with the atmosphere], the “knocked-out GPA1” plants wilted due to uncontrolled water loss to the atmosphere.

See also GENE, CELL, MITOSIS, G-PROTEINS,

PLANT HORMONE, ABSCISIC ACID, KNOCKOUT

(GENE).

GPCRs Acronym for G-Protein-Coupled Recep-

tors. See also G-PROTEIN-COUPLED RECEPTORS.

Graft-Versus-Host Disease (GVHD) The rejection of transplanted organs by the recipient’s immune system. Also known as hyperacute rejection. It is caused by the attack of the recipient’s T lymphocytes (T cells, a certain class of white blood cells) on the transplanted organ. The recipient’s T cells are able to distinguish between self and foreign cells, and are hence able to recognize the foreign (nonself) cells of the transplanted organ. They then, naturally, try to destroy the “foreign invaders” in the body. This constitutes rejection of the transplanted organ. From this it should be understood that there is nothing wrong with the body, but that it is behaving exactly as it should. See also CELLU-

LAR IMMUNE RESPONSE,

XENOGENEIC ORGANS, FIBROBLASTS, CYCLOSPORIN.

Gram Molecular Weight T h e w e i g h t i n grams of a compound that is numerically equal to its molecular weight; the weight of one mole (6.02 × 1023 molecules). See also

MOLECULAR WEIGHT, MOLE.

Gram Stain Devised by Hans Christian Joachim Gram in 1884, this is a test that illuminates the composition/makeup of the physical structure of the cell wall of bacteria being tested. It is utilized to judge the effectiveness of a given chemical compound (e.g., an antibiotic) against bacteria types. The test consists of a differential staining procedure, which allows most bacteria to be visually separated into two groups, known as GramPositive (G+) and Gram-Negative (G-).

An antibiotic is defined in terms of the group of (pathogenic) bacteria that it is effective against, which is known as that antibiotic’s “spectrum of activity.” An antibiotic is said to have a spectrum of activity against gram-positive bacteria, gram-nega- tive bacteria, or the bacteria of both groups. An antibiotic that is effective against both groups of bacteria is termed “broad spectrum” or “wide spectrum.” See also BACTE-

RIA, GRAM-POSITIVE (G+), GRAM-NEGATIVE (G- ),

PATHOGENIC, CELL, ANTIBIOTIC.

Gram-Negative (G-) Pertaining to one of the most important ways of classifying bacteria by means of the differences in the way they stain. The set of bacteria that are not able to be stained (blue) when treated with the gram staining procedure. Gram negativity (and gram positivity) is conferred not by the chemical constituents of the bacteria, but rather by the physical structure of the bacteria cell wall. The staining procedure involves the staining of all cells in a sample with a blue dye. Gram-negative bacteria have a very thin peptidoglycan cell wall (capsule). Hence, the washing procedure, which is an integral part of the overall staining procedure, washes out the blue dye (known as crystal violet). This leaves the gram-negative bacteria colorless. The cells are then stained with a red acidic counterstain (dye) such as acid fuchsin or safranine. After treatment with counterstain, the gramnegative cells are red and the gram-positive cells are blue. See also GRAM-POSITIVE (G+),

BACTERIA, CELL, GRAM STAIN.

Gram-Positive (G+) Pertaining to bacteria, holding the color of the primary stain (blue) when treated with Gram’s stain (a commercial staining agent), or Gentian violet solution. In

contrast to the gram-negative bacteria, the gram-positive bacteria possess a much thicker peptidoglycan cell wall (capsule). Because of this, the blue crystal violet dye (with which the bacteria were stained) does not wash out of the cell and the bacteria appear blue under the microscope. See also

GRAM-NEGATIVE (G-), BACTERIA, CELL, GRAM

STAIN, CAPSULE.

Granulation Tissue A mixture of proteins and
cells produced by the fibroblast growth that
results from a wound. See also FIBROBLASTS,
PROTEIN.
		G
Granulocidin A protein produced	by white
blood cells, which has demonstrated (in the
laboratory) an ability to kill a broad spectrum
of pathogens. See also PATHOGEN, PROTEIN.
Granulocyte Colony Stimulating Factor
(G-CSF) A colony stimulating factor (CSF;
a protein) that stimulates production of gran-
ulocytes, particularly neutrophils. See also
COLONY STIMULATING FACTORS, GRANULOCYTES,
NEUTROPHILS.
Granulocyte-Macrophage Colony Stimulating
Factor (GM-CSF) (or Granulocyte-Mono-
cyte Colony Stimulating Factor) A colony
stimulating factor (CSF; a protein) that stim-
ulates production of granulocytes/macroph-
ages/monocytes. See also COLONY STIMULATING
FACTORS (CSFs), MACROPHAGE, MONOCYTES.
Granulocytes (polymorphonuclear	granulo-
cytes) Phagocytic (scavenging,	ingesting)

cells that are part of the immune system. When their cell nucleus is segmented into lobes and they have granule-like inclusions within their cytoplasm (the neutrophils, eosinophils, and basophils), they are collectively known as polymorphonuclear granulocytes.

See also PHAGOCYTE.

GRAS List A list of food additives/ingredients considered to be Generally Recognized as Safe, by the U.S. Food and Drug Administration (FDA). This list of additives is judged to be safe by a panel of FDA pharmacologists and toxicologists, who base their judgment upon data that is available for each ingredient. In practice, those additives for which extensive experience of common use in foods (without known ill effects) has been accumulated over time (e.g., common table salt) are often approved by the FDA due more to the

© 2002 by CRC Press LLC

“common use factor” than to any toxicology data, per se. See also FOOD AND DRUG ADMIN-

ISTRATION (FDA), DELANEY CLAUSE, PHARMACOL-

OGY, CANOLA.

Grass Pea See GLUCOSINOLATES.

Green Fluorescent Protein A protein that is

		naturally present within the jellyfish Aequo-
		rea victoria. Green fluorescent protein
		(GFP) is utilized by scientists to “mark” cer-
		tain endpoints in experiments (at which
		point the green light signals that endpoint
		was reached). See also FLUORESCENCE, PROTEIN,
		GENE EXPRESSION MARKERS.
	G
		GRF See GROWTH HORMONE RELEASING FACTOR.
		GRH See GROWTH HORMONE RELEASING FACTOR.
		Group of National Experts on Safety in Bio-
		technology See GNE.
		Growth (microbial) An increase in the num-
		ber of cells. See also GENERATION TIME.
		Growth Curve The change in the number of
		cells in a growing culture as a function of
		time. See also GENERATION TIME.
		Growth Factor A specific substance that must
		be present in the organism’s tissues (when
		in vivo) or growth medium (when in vitro)
		in order for the growth-factor-specific cells
		to grow/multiply. See also FIBROBLAST
		GROWTH FACTOR (FGF), NERVE GROWTH FACTOR
		(NGF), EPIDERMAL GROWTH FACTOR (EGF), VAS-
		CULAR ENDOTHELIAL GROWTH FACTOR (VEGF),
		ANGIOGENIC GROWTH FACTORS, ANGIOGENIN,
		BONE MORPHOGENETIC PROTEINS (BMP).
		Growth Hormone (GH) A h o r m o n e p r o -
		duced by the anterior pituitary gland. This
		hormone is a protein (somatotropin) and can
		be obtained from the bodies of animals, or
		produced by genetically engineered micro-
		organisms. Its major action in humans
		(human growth hormone) is a generalized
		stimulation of skeletal growth. However,
		human growth hormone (HGH) is also
		known to affect the growth of other tissues,
		to be important in fat, protein, and carbohy-
		drate metabolism, and to enhance the effects
		of various other hormones. See also BOVINE
		SOMATOTROPIN (BST), PORCINE SOMATOTROPIN
		(PST), PITUITARY GLAND.
		Growth Hormone-Releasing Factor (GRF or
		GHRF) Also termed growth hormone-
		releasing hormone (GRH). A factor that

causes the release of growth hormone, it is 44 amino acids in length. See also GROWTH

HORMONE (GH), GROWTH FACTOR, AMINO ACID,

HORMONE.

GT-AG Rule Describes the presence of these constant dinucleotides at the first two and last two positions of introns of nuclear genes. See also INTRON, GENE.

GT/PT Correlation Abbreviation for Genotype/Phenotype Correlation. See also GENO-

TYPE, PHENOTYPE.

GTO Abbreviation for Gene Technology Office.

See also GENE TECHNOLOGY OFFICE.

GTP See GMP.

GTPases Guanosine triphosphatases. These are G-proteins (enzymes) which are crucial for growth, movement, and maintenance of the cell’s shape. When active, GTPases are bound to cell membranes (surfaces) by an isoprene molecule (receptor). See also G-PRO-

TEINS, ENZYME, CELL, PHOSPHORYLATION, RECEPTORS, PROTEIN.

GTR See GENE TECHNOLOGY REGULATOR (GTR).

GTS Glyphosate tolerant soybean. See also

HERBICIDE-TOLERANT CROP, SOYBEAN PLANT, CP4

EPSPS, GLYPHOSATE.

GTS Glufosinate-ammonium tolerant soy-

bean. See also HERBICIDE-TOLERANT CROP, SOY-

BEAN PLANT, PAT GENE, GLUFOSINATE.

Guanine A purine base. It occurs naturally as a fundamental component of nucleic acids.

See also PURINE, NUCLEIC ACIDS.

GURTs See GENETIC USE RESTRICTION TECHNOL-

OGIES.

GUS See GUS GENE.

GUS Gene A gene that codes for production of β-glucuronidase (i.e., GUS protein) in Escherichia coli bacteria. The GUS gene is commonly utilized as a “marker gene” for genetically engineered plants. β-glucuronidase causes a color change, in the presence of the chemical 5-bromo-4-chloro-3-indoyl-beta-D- glucuronic acid, by cleaving (‘cutting’) a glucuronic acid molecule off the 5-bromo-4- chloro-3-indoyl-beta-D-glucuronic acid. The (remaining) molecule is an insoluble blue dye.

See also GENE, CODING SEQUENCE, ESCHERICHIA COLIFORM (E. COLI), MARKER (GENETIC MARKER),

GENETIC ENGINEERING.

© 2002 by CRC Press LLC

Gut-Associated Lymphoid Tissues (GALT)

A variety of specialized lymph-reticular tissues that line the inside of an animal’s digestive system. GALT include Peyer’s Patches, the appendix, and small solitary lymphoid

tissues in the gut. They constitute the intestinal immune system (response to antigens).

See also LYMPHOCYTE, PEYER’S PATCHES, ANTI-

GEN, HUMORAL IMMUNITY, CELLULAR IMMUNE

RESPONSE, “EDIBLE VACCINES”, PLANTIGENS.

G

© 2002 by CRC Press LLC